Diamond bits and similar tools



May 9, 1967 N. E. GARNER DIAMOND BITS AND SIMILAR TOOLS 3 Sheets-Sheet 1Filed March 22, 1965 o A o A AP= 500 P51.

5 AP: I000 as.

V AP= aooo P.S.l.

3 I woznom wumou ZFZONEOI VERTlC /?L FORCE POUNDS FIG. 2

ROTATION Norman E. Garner INVENTOR- QA ATTORNEY y 9, 967 N. E. GARNER3,318,399

DIAMOND BITS AND SIMILAR TOOLS Filed March 22, 1965 5 Sheets-Sheet 2 APRANDOM SET d Ill g Em 3 F16 3 h! I 3 5 o E I U E l I l L I I I I l I 0IO so vsrmcm. FORCE ouuos "95% AF 500 P.s.l.

J g 'i' E O RANDOM SET 4 U I 5 U 9 2 E SELECTIVELY MOUNTED u c I l l I IL I l l l 0 I0 20 so 40 so VERTICAL FORCE PDUNDS |5 AP uooo P.S.I.

a, U 3 Z a! EIO /IA FIG 5 u SELECTIVELY MOUNTED 1: A 8 g m RANDOM SET 05 A/ o l l l l I I I l l I VERTICAL FORCE POUNDS Norman E'.-Gorner I NVEN TOR.

ATTORNEY May 9, 1967 N. E. GARNER DIAMOND BITS AND SIMILAR TOOLS I5Sheets-Sheet 5 Filed March 22, 1965 AP: 2000 am.

SELECTIVELY MOUNTED RANDOM SET 15 A 0 5 O 4 s D N u 0 P -v E m m6 L AF wT R E v 0 2 kmzum O SELECTIVELY MOUNTED STONES WATER A SELECTIVELYMOUNTED STONES MUD O RANDOM SET STONES WATER A RANDOM SET STONES MUD BITWEIGHT POUNDS FIG. 7 Normdn E. Garner INVENTOR.

M w E. m

ATTORNEY United States Patent f 3,318,399 DIAMOND BITS AND SIMILAR TOOLSNorman E. Garner, Houston, Tex., assignor to Esso Production ResearchCompany, a corporation of Delaware Filed Mar. 22, 1965, Ser. No. 441,6633 Claims. (Cl. 175329) The present invention relates to tools forpenetrating rock and similar material and is particularly concerned withdiamond drill bits, reamers, underreamers and related tools used in thepetroleum and mining industries.

Diamond drill bits and similar tools are widely used for drillingboreholes in subterranean formations. The performance of such toolsdepends in part upon the way in which the diamonds are set in thematrix. Due to differences in the spacing of the carbon atoms in thediamond lattice, most diamonds are stronger in certain directions thanin others. The direction of maximum strength is normally parallel to thediagonal of an internal cube face in the lattice. By placing eachdiamond so that the resultant of the forces applied to it is transmittedin this direction, the performance of a bit or similar tool cangenerally be improved. The required placement of a diamond is normallydetermined by reference to its external structure. With octahedralstones, each diamond should be positioned so that an octahedral facecontacts the underlying formation at a negative rake angle of about 30.Cubic and dodecahedral diamonds must be set in somewhat diiferentpositions. The placement of the stones in this manner is generallypractical only where they have well defined, easily discernible faces.Where the stones are worn, fractured or composited so that the faces cannot be readily identified, a study of their in ternal crystallinestructures becomes necessary. The added cost of such a study tends tooffset any savings that might be realized through selective placement.The diamonds on most commercial bits and similar tools are therefore setwithout regard for the crystalline faces. Tools containing such diamondsare often referred to as random set tools.

It is therefore an object of the present invention to provide improveddiamond bits and similar tools which will penetrate subterraneanformations more effectively than random set tools available in the past.Another object is to provide improved bits and similar tools on whichdiamonds are selectively positioned to secure better performance withoutsubstantially increasing the diamond setting costs. the invention isdescribed in greater detail hereafter.

In accordance with the invention, it has now been found that theperformance of diamond drill bits, reamers, underreamers and similartools containing irregularly shaped diamonds lacking well definedcrystalline faces can be substantially improved by orienting at least amajority of the diamonds so that the angle between the surface of eachdiamond immediately adjacent the drilling point and a plane passingthrough the apex of the drilling point parallel to the matrix is greaterat the leading edge of the stone than at other points. Tests have shownthat this method of setting the diamonds permits substantially higherpenetration rate than can be obtained with random set tools available inthe past and does not result in excessive wear of the diamonds. It doesnot require a detailed crystallographic study of each diamond, is notlimited to the use of high quality stones having easily discerniblecrystalline faces, is applicable to salvaged diamonds or irregularshape, and can be carried out without substantially increasing theoverall setting cost per tool. As a result, the method has much widerapplicability that diamond setting methods employed in the past.

The nature and objects of the invention can best be Still other objectswill become apparent as v 3,318,399 Patented May 9, 1967 understood byreferring to the following detailed description and to the accompanyingdrawing in which:

FIGURE 1 is an enlarged sectional View of a portion of a diamond drillbit and the underlying formation showing the placement of a diamond inthe matrix;

FIGURE 2 is a graph showing the relationship between the vertical forceapplied to a diamond and the resultant horizontal force transmitted tothe underlying formation;

FIGURE 3 is a graph showing the volumes of rock removed by a diamondmounted in accordance with the invention and a diamond mounted in theconventional manner with zero pressure differential across the face ofthe rock formation;

FIGURE 4 is a graph showing the volumes of rock removed by the twodiamonds under a fluid pressure differential of 500* lbs. per squareinch;

FIGURE 5 is a graph showing the volumes of rock removed by the twodiamonds under a pressure differential of 1000 lbs. per square inch;

FIGURE 6 is a graph showing the volumes of rock removed by the twodiamonds under a pressure differential of 2 000 lbs. per square inch;and,

FIGURE 7 is a graph showing the difference in the drilling rate obtainedwith a full size bit set in accordance with the invention and thatobtained with a random set bit under identical conditions.

The cross sectional view shown in FIGURE 1 of the drawing is taken alonga plane extending in the direction of relative motion between thediamond and the adjacent underlying formation. The diamond 11 isembedded in a metallic matrix 12 on the lower part of the tool body andextends downwardly below the lower surface of the matrix in contact withformation 13 at point 14. The body construction and the matrixcomposition may be of any conventional type. The diamond shown istypical of the bortz commonly used on drill bits and similar toolsemployed in the petroleum and mining industries. These diamondsgenerally range between about 1 per carat and about 100 per carat insize, the size selected depending on the particular type of service forwhich the tool is intended. Diamond drill bits employed for penetratingrelatively soft rock formations, such as those encountered in mostoilfield drilling operations, are generally set with diamonds rangingfrom about 10 per carat up to about 1 per carat in size; while smallerstones between about 8 per carat and about 60 per carat are morefrequently employed on bits intended for penetrating hard formations inthe mining industry. As indicated in FIGURE 1, these diamonds aregenerally rounded stones of irregular shape and seldom have theclassical cubic, octahedral or dodecadral configurations referred to indiscussions of the orientation of diamonds. Since such diamonds lackeasily discernible faces, a detailed study of the crystalline structureof each stone must be made by a skilled crystallographer before thestone can be oriented with respect to an internal cube face. The cost ofsuch orientation is generally prohibitive, particularly in the case oflarge bits on which many small diamonds are employed.

The point 14 on the diamond shown in FIGURE 1 of the drawing is referredto as the drilling point. This point, normally selected by the diamondsetter by visually examining the stone, is a relatively sharp corner orapex with an included angle that is generally greater than It may or maynot correspond to a cubic or rectangular pyramidal point on a cubic,octahedral or dodecahedral diamond. Diamonds of the type shown areseldom symmetrical and hence the longitudinal axis of such a stone isnormally taken as the straight line interconnecting the drilling pointand the most remote opposed point on the diamond surface. On most randomset tools, the longitudinal axis of each diamond will extend atapproximately right angles to the surface of the matrix in which thediamond is embedded. The diamond surfaces adjacent the drilling pointmay extend upwardly at various angles with respectto the longitudinalaxis. On each stone, there will normally be one surface which extendsupwardly from the drilling point ata greater angle than do the others.On random set tools, differences in diamond configuration adjacent thedrilling point are nottaken into consideration.

The present invention is based on the discovery that the performance ofdiamond bits and similar tools can be improved significantly byselectively mounting the individual stones withoutjregard for theircrystallinefaces :and'internal structure. The setting of at least amajority of the diamonds, preferably all of them, so that the anglebetween the diamond and underlying formation at the point of contact isgreater at the leading edge than at the trailing edgeperrnitssubstantially higher drilling rates than can normally be obtained withrandom set tools I and yet avoids the high costs associated withconventional diamond orientation methods proposed in the past.

This type of mounting, illustrated in FIGURE 1 of the drawing-requiresthat the angle facing in the direction of relative motion of the diamondwith respect to the underlyingformation be greater than the angle facingaway from the direction of relative motion.- Angle a in'FIGURE 1 is thusgreater than angle ,8. Each. diamond is preferably rotated about itslongitudinal axis todetermine the surface which extends upwardly fromthe drilling point at the greatest angle with respect to a plane throughthe drilling point at right angles to the longitudinalaxis. The stone isthen mounted so that this surface will face in the direction in whichthe diamond is to move relative to the underlying formation. On a drillbit or similar tool where the motion takes place about a fixed .axis,the stone should be mounted so that the selected surface faces a't rightangles to a radius through the fixed axis. On tools designed 'forrectilinear motion, the surface selected should face in the direction ofmotion. In either case, the setting of the diamonds as describedincreases the horizontal force which can be applied to the formation bymoving the diamond in contact with the formation under a given verticalload. The horizontal forcev component is directly related to the I.ene'rgytransmitted to the rock at constant diamond pene-,

trationkand hence an increased drilling rate, is obtained.

' surface adjacent the drilling point and then gluing it in a shallowdepression in inner wall of a refractory moldv with this surface facingin the direction of relative mo- .tion of'the diamond with respect tothe formation, most diamonds can be set rapidly. The crystallinestructure of'the diamond does not haveto be considered and henceparticular faces need not be identified with respect to thecrystallat-tice. Once the diamonds have been glued in place or otherwisemounted in the mold, the

supporting matrix can be formed by the liquid phase sintering of asuitable metallic powder or mixture of This member was then placed inthe high pressure chamher above a rock sample mounted in a rotatablesample holder. Strain gauges mounted on the memberand associated partswere connected to a recording device for measuring the forcestransmitted to the rock as it moved beneath the diamond. The rockemployed was an Indiana limestone. In each test the diamond was forcedinto the rock under various vertical loads and the horizontal force wasthen measured as the rock was rotated. The volume of the groove formedwas also measured. Tests were carried out at differential pressuresacross the face of the formation up to 2000 lbs. per square inch. The

' results of these tests are shown in FIGURES 2 through 6 of thedrawing.

FIGURE 2 shows the results of tests carried out with the diamond in twodifferent positions. In the first series of. tests, the diamond waspositioned so that the angle between the diamond surface and the rocksample at the point of contact was greater at the leading edge than atthe trailing edge. Curve A in FIGURE 2 depicts the results. In thesecond series, the diamond was displaced 180 from the earlier position.The results of these later tests are shown by curve B. It will be notedthat the data points give two well-defined curves when the measuredhorizontal force is plotted against the applied vertical force; For agiven vertical force, the horizontal forces were much greater with thediamond mounted so that the angle at the leading edge exceeds that atthe trailing edge. This was true regardless of the differential pressureacross the face of the rock sample. Since the measured horizontal forceis directly proportional to the amount of energy transmitted to therock, it is apparent that the diamonds positioned in accordance with theinvention were considerably more eifective than those positioned so thatthe angle at the trailing edge exceeded that at the leading edge.

The results shown in FIGURE 2 of the drawing are confirmed by the dataset forth in FIGURES 3 through 6. The latter figures show groove volumeas a function for, (1) diamonds which were mounted so that the angle atthe leading edge exceeded that at the trailing edge and powders.Conventional infiltration or'high pressure sintering techniques, may beused.

The advantages of setting the diamonds on a bit or similar tool in themanner described above can be seen by considering the results of testscarried out in a high pressure chamber provided with meansfornneasuring- (2) random set diamonds. It. can be seen from the curvesthat the groove volume per inch of travel was sig nificantly greater forthe diamonds positioned in accordance with the invention than for therandom set diamonds. In each case the positioning of the diamonds sothat the angle between the diamond surface and the underlying formationat the point ofcontact was greater at the leading edge than at thetrailing edge permitted the removal or more rock than could be removedwith the random oriented stones. The differential pressures across theface of the formation had only a slight effect on the volume of rockremoved.

FIGURE 7 is in the drawing depicts the results obtained with two 5 inchdiamond bits in drilling through Indiana limestone. Two series of testswere carried out, one using water as the drilling fluid and the otheremploying a conventional bent-unite mud. A rotary speed of revolutionsper minute and a fluid circulation rate of gallon per minute wereemployed in all of the tests. ,The two bits used were identical exceptfor the setting of the diamonds. In one case the diamonds were randomset in the usual manner. In the other case, each diamond was positionedso that the angle between the diamond surface and the underlyingformation at point of contact was greater at the leading edge than atthe trailing edge. Each bit was tested at three different weights. Thepenetration rate was determined by measuring the time required to drilla fixed distance in the limestone. As can be seen from the drawing, thebit on which the diamonds were set in accordance with the inventionconsistently outperformed the random set tool. The drilling rate wasabout to percent higher for the bit of the invention. These results showthat the setting of at least a majority of the diamonds on bits andsimilar tools so that the angle at the leading edge of each stoneexceeds that at the trailing edge has pronounced advantages,

Although the invention has been described above in terms of diamonddrill bits, it will be understood that the improvement shown is notlimited to such tools. The setting of the diamonds on core bits,reamers, underreamers and similar tools employing diamonds to penetratesubterranean formation-s so that the angle at the leading edge of atleast a majority of the diamonds is greater than that at the trailingedge is advantageous.

What is claimed is:

1. A tool for penetrating rock and similar materials which comprises:

(a) a tool body composed at least in part of a metallic matrix; and,

(b) a plurality of rounded diamonds of irregular shape embedded in thesurface of said matrix and protruding therefrom, said diamonds includingdrilling points extending beyond the matrix surface for engaging thematerial to be penetrated and at least a majority of said diamonds beingoriented so that the angle between the diamond surface at the leadingedge of each stone and a plane passing through the apex of the drillingpoint parallel to the matrix surface is greater than the angle betweenthe diamond surface and said plane at the trailing edge of said stone.

2. A diamond bit for drilling boreholes in the earth which comprises:

(a) a bit body including a metallic matrix at the lower end thereof;and, er end thereof; and

(b) a plurality of rounded diamonds of irregular shape embedded in thelower surface of said matrix and protruding therefrom, said diamondsincluding drilling points extending beyond the matrix surface forengaging the underlying formation and at least a majority of saiddiamonds being oriented so that the most nearly vertical surfaces onsaid diamonds immediately adjacent the drilling points face in thedirection of bit rotation.

3. A diam-0nd bit for drilling boreholes in the earth which comprises:

(a) a tubular bit body provided with a metallic matrix at the lower endthereof; and

('b) a plurality of diamonds embedded in the lower surface of saidmatrix, the crystalline axes of said diamonds being random oriented,each of said diamonds including a drilling point projecting downwardlybelow the lower surface of the matrix for engaging the underlyingformation, and at least a majority of said diamonds being oriented sothat the angle between the diamond surface immediately adjacent thedrilling point and a plane passing through the apex of the drillingpoint parallel to the surface of the matrix surrounding each diamond isgreater in the direction of relative motion of said diamond with respectto said underlying formation than at other points about the diamondsperiphery.

References Cited by the Examiner UNITED STATES PATENTS Re. 23,632 3/1953Zublin 329 2,371,488 3/1945 Williams 175330 3,027,952 4/1962 Brooks175329 3,058,535 10/1962 Williams 175-330 CHARLES E. OCONNELL, PrimaryExdmin'er.

R. E. FAVREAU, Assistant Examiner.

1. A TOOL FOR PENETRATING ROCK AND SIMILAR MATERIALS WHICH COMPRISES:(A) A TOOL BODY COMPOSED AT LEAST IN PART OF A METALLIC MATRIX; AND, (B)A PLURALITY OF ROUNDED DIAMONDS OF IRREGULAR SHAPE EMBEDDED IN THESURFACE OF SAID MATRIX AND PROTRUDING THEREFROM, SAID DIAMONDS INCLUDINGDRILLING POINTS EXTENDING BEYOND THE MATRIX SURFACE FOR ENGAGING THEMATERIAL TO BE PENETRATED AND AT LEAST A MAJORITY OF SAID DIAMONDS BEINGORIENTED SO THAT